merge: feat/wf5-securestorage into the 0.0.50 integration line

Brings the per-agent harness-home work (FLEET_SEAT) onto the release line.
Clean merge, no conflicts.

packages/mosaic/src/commands/fleet.spec.ts

@@ -82,6 +82,8 @@ describe('registerFleetCommand', () => {
     expect(fleet).toBeDefined();
     expect(fleet!.commands.map((command) => command.name()).sort()).toEqual([
       'add',
+      'adopt',
+      'agent',
       'apply',
       'backlog',
       'create',
@@ -91,6 +93,7 @@ describe('registerFleetCommand', () => {
       'init',
       'install',
       'install-systemd',
+      'launch',
       'migrate-v1',
       'persona',
       'plan',